The purchase of 15,000 put options — which essentially allow people to sell their stock at a predetermined price — would have allowed the man to make a substantial profit in the event of a big drop in Dortmund's share following the bombing.

"If the shares of Borussia Dortmund had fallen massively, the profit would have been several times the initial investment," the prosecutor's office said. The office added that if any players had been seriously injured or even killed, that would have been a realistic possibility.

The bus of the Borussia Dortmund football team was struck by three explosions. Two people were injured in the explosions: Bartra and a police officer who was near the bus at the time of the attack.